Counting each version individually, there are currently 24 games in the series internationally, 25 in Japan, and 15 in South Korea. Counting paired individual versions as a single release, there are currently 14 games in the series internationally, 15 in Japan, and 8 in South Korea.

Prior to Generation VI, it was standard for the Western releases of the core series games to include the label Version in their title, although this was also seldom used by the Japanese releases. In Japan and South Korea, the series is called the Pocket Monsters Series (Japanese: ポケットモンスターシリーズ[4], Korean: 포켓몬스터 시리즈[5]), as core series games all contain Pocket Monsters (Japanese: ポケットモンスター, Korean: 포켓몬스터) in their title, whereas side series and spin-off games use Pokémon (Japanese: ポケモン, Korean: 포켓몬) instead.

Classification

Content model

While there are no strict rules that make a game a core series game, and previously assumed rules are continuously broken, the games generally have a similar plot and mechanics.

The player begins the game in a small town or city of a given region, having no Pokémon of their own. Through a course of events, the player will receive a starter Pokémon from the region's Pokémon Professor; the starter Pokémon is always a choice of three, a Grass, Fire, or Water type, and the character who will become the player's rival will choose (or already have) the Pokémon whose type is super effective against that of the player's choice. (The exceptions to this are Pokémon Yellow, in which the player starts with Pikachu and the rival starts with Eevee, and Pokémon Black and White, in which the player has two rivals, who each choose one of the starter Pokémon not picked by the player.)

After this point, the player begins to journey across the entire region (each with their own cities and towns, themselves connected by routes), capturing any wild Pokémon he or she chooses to, and using a party he or she assembles to take on the eight Gym Leaders of the region. Alongside encounters with both other Trainers and repeated interactions with their rival, the player must also stop the plans of a villainous team, whose plans often involve the manipulation of Legendary Pokémon.

After all eight Gym Leaders have been defeated, the player can enter the Pokémon League, where the Elite Four and Champion await challengers. The Champion of the region is often introduced prior to the player's Pokémon League challenge, and may aid the player as he or she continues his or her adventure.

Though the game can be considered over as soon as the player has defeated the Champion, there is still post-game content. Often there is a post-game plotline and locations and facilities that could not be previously accessed. Since Pokémon Crystal, there is usually at least one facility specifically dedicated to battling. The overarching goal is the completion of the Pokédex; after this has been done, the player will receive a diploma for completing the regional Pokédex and, starting in Generation III, another for completing the National Pokédex. Another task was added in Generation III in order to fully complete the game: obtaining all Trainer Cardstars.

Another element that characterizes a core series game is that the geography of regions includes at least one water route, a mountain, several caves, a forest, as well as a final route leading up to the Pokémon League called Victory Road.

Release model

While releases continue to break patterns, there is an overall model that the release of new core series games follows.

When a generation of Pokémon games begins, a pair of games is always released. These paired versions feature virtually the same storyline as each other, but each version-exclusive Pokémon differ, and some other elements are usually slightly different. This encourages trading, as it is required in order to complete the Pokédex.

A solitary version is later released with several minor storyline tweaks, but taking place in the same region and following the same basic storyline. Like the paired versions before it, it will always lack some of the Pokémon but will also contain some of those species missing from either of them; thus, a player of the solitary version must link together with the paired versions to complete the Pokédex as well.

Sometimes, a secondary set of paired versions may be released. These paired versions are usually remakes of earlier titles and are not accompanied by a solitary version, since the latter's additions and changes are taken into consideration. Generation V broke with tradition by releasing a second pair of games as a sequel to the primary paired versions instead of a remake.

New generations are typically announced and marketed every three to four years.

In all generations, there are some Pokémon that cannot be encountered until after the player enters the Hall of Fame. These may be legendary Pokémon, such as Mewtwo, or simply Pokémon that are not part of the game's regional Pokédex.

Before the release of a new generation, new Pokémon are often used to promote the new games by including them in the anime or in spin-off games.

Timeline

Several pieces of content in the core series Pokémon games depend on the games having a timeline, but a complete timeline cannot be drawn from the games themselves. In May 2014, Game Freak employee Toshinobu Matsumiya posted a timeline of the core series Pokémon games on Twitter.[6] However, the tweet has since been deleted.

It is unknown if the aforementioned timeline also applies to all solitary versions and remakes. Furthermore, Zinnia suggests that there are alternate universes.

Trivia

Nintendo has trademarked several titles which have not currently been used but which fit the naming scheme of the core series games.[7] These include Pokémon Brown[7], Pokémon Gray[7], and Pokémon Delta Emerald[8].